To further utilize the pseudo-saturation map \(\mathbf {x}_{stau}\) , we leverage a linear filter to augment the variances between the smoothed image content and the exposed perturbed regions.
Such linear filters have been widely used in steganalysis of digital images [1]}, [2]}, [3]}, [4]}, [5]}, and it has also been used for AE detection in [6]}. Different from [6]}, we apply the filters on the pseudo-saturation maps instead of on the natural images.
As shown in Figure REF  (c), the distinction between the noise and the image content \(\mathbf {x}_{stau}\)  is further amplified. Therefore, such linear filters can further help us differentiate AEs from clean samples.
